Fujitsu flip-phone is device of choice for Japan's philanderers

Fujitsu's F-Series phones have become known as "infidelity
phones" in Japan because of some of their privacy features which
make it easy for adulterers to hide calls and messages from
contacts marked as "private".

The flip-phone has been on the market for more than five years,
but has been outed in the Wall Street Journal by a Japanese dating blogger who goes
by the name of Bakanabe as device of choice for men (and,
presumably, women) who want to hide certain calls or texts from
their partners. It has a privacy mode that allows the user to
designate certain contacts as private. If one of those contacts get
in touch via calls, emails or text messages, the phone creates none
of the usual call logs or other such evidence. Instead, there will
be a subtle change in the colour or shape of the battery signs or
signal bars.

This privacy mode can then be turned off using a secret
combination of keys, which allow the hidden calls and messages to
be revealed. This means that a phone can be left out around a
suspicious partner without any risk of the phone's owner being
caught out. The phone has become so popular with cheaters that
it has been given the nickname "uwaki keitai", or "infidelity
phone".

Fujitsu launched the feature in 2002, but has never marketed it
as a phone for philanderers. Rather, it focuses on security and
privacy.

The company is gradually phasing out these flip-phones in favour
of smartphones, although it has migrated a version of the privacy
function (although the latest version requires an additional app
download).

This is not the first time that a service has been heralded for
helping cheaters hide their misbehaviour. In 2011 an app called Loky Plus launched, allowing people to lead double lives on
their smartphones, hiding texts and phone calls from prying
partners' eyes.

The app sets up a secure area on your mobile phone, where you
can put private contacts. Loky Plus then manages the calls and
messages, storing the data separately from the rest of the phone.
Call and Text Eraser (CATE) offers a similar level of
security.